Acerocnema incisa, Iwasa, 2021

Iwasa, Mitsuhiro, 2021, Three new species and six new records of Scathophagidae (Diptera) from Japan with a key to the Japanese genera, Zootaxa 4981 (3), pp. 531-553 : 532-534

Acerocnema incisa sp. nov.

( Figs 1–6 )

[Japanese name: Kiashi-kuchiboso-funbae]

Type material examined. Holotype ♂, Japan: Inada, Obihiro City, Tokachi , Hokkaido, 18. v. 2014, leg. H. Torikura ( OUAVM) . Paratypes: Hokkaido, 3 ♂, 4 ♀, same locality as holotype, 15-25. v. 2014, leg. H. Torikura ( OUAVM) ; 1 ♂, Kawanishi, Obihiro City, Tokachi , 11. v. 2014, leg. H. Torikura ( OUAVM) ; 6 ♂, 34 ♀, Otofuke Town, Tokachi , 18-21. v. 2017, leg. H. Torikura ( OUAVM) . Kyushu , 2 ♀, south of Ito campus, Kyushu Univ. Fukuoka City , 4. iv. 2015, leg. D. Kato ( OUAVM) .

Diagnosis. Acerocnema incisa sp. nov. can be recognized by thorax with grey microtrichose, dorsal setulae on apical portion of vein R 1 of wing, and male surstylus anterodistally dilated

Description. Male. Head ( Figs 1, 2 ): eyes reddish-brown; frons reddish; ocellar triangle black; face, parafacial, and gena yellow; occiput black and shining; postpedicel black and enlarged, approximately 2.5 times long as wide; arista basally pubescent and apically short-haired, approximately same length as postpedicel; palpi yellow and clavate; proboscis slender and sclerotized with reduced labella; vibrissal angle with a strong yellow vibrissa. Chaetotaxy (black): 3-4 fr, 3 or (1 proclinate, 1 lateroclinate, 1 latero-reclinate), 1 oc, 1 poc, 1 vti (strong), 1 vte. Thorax: wholly black; prescutum and scutum thinly grey microtrichose, with two longitudinally shiny stripes on scutum and with inconspicuous hairs ( Fig. 1 ); scutellum shining; all thoracic pleura grey microtrichose; proepisternum anteriorly with hairs; anepisternum posteriorly hairy; katepisternum sparsely with long hairs; anepimeron, meron, and katatergite bare; metanotum shining in lower part. Chaetotaxy (yellow): 2 pprn, 2 npl, 1+1 ial, 1 sa, 2 pa, 1+3 dc, 1 bsc, 1 apsc,1 prepst, 1 prepm, 6-7 anepst, 1 kepst. Wings: hyaline, slightly tinged with brown; veins brown; R 1 with dorsal setulae on apical portion; veins R 4+5 and M 1 almost parallel; vein A 1 +CuA 2 disappear well before wing margin; calypter yellow, with hairs marginally; halteres yellow. Legs: entirely yellow, covered with hair-like setulae; fore femur with several pd setae distally; mid and hind femora with preapical setae; fore tibiae with 1 ad at two-fifths; mid tibia 1 ad at near half and subapical setae; hind tibia with 2 ad at one-third and half, and subapical setae; all tarsi yellow; fifth tarsomere somewhat compressed. Abdomen: tergites black and shining, covered with short hairs; sternites II to IV longitudinally rectangular, sparsely covered with hair-like setulae; sternite V ( Fig. 3 ) deeply bilobate posteriorly; epandrium ( Fig. 4 ) developed and sparsely with hairs but without setae; surstyli ( Figs 4, 5 ) long, slender, curved and dilated antero-apically; aedeagus ( Fig. 4 ) slender, apically swollen and membranous; epiphallus flattened, curved and pointed apically; parameres rod-shaped; hypandrium large, thick, and V-shaped; cerci stout and membranous, covered with hairs.

Female. Basal and ventral portions of postpedicel, postpronotum and proepisternum paler than those of male; abdominal tergites II to VI centrally black and laterally yellow to light brown; sternites III to VI longitudinally elongate; segments (tergites and sternites) VII to VIII ( Fig. 6 ) compressed and tergite VIII strongly sclerotized; cerci, epiproct, and hypoproct weakly pigmented. Other characteristics as those of male.

Length (♂ ♀). Body, 4.0–4.2 mm; wings, 4.0–4.3 mm.

Distribution. Japan (Hokkaido and Kyushu).

Etymology. This new species is named after the scientific name of the flower species which has a close relationship with this fly.

Remarks. This new species is similar to A. kishimotoae Iwasa in general appearance, but differs from it in having the following characteristics: frons reddish; scutum grey microtrichose with inconspicuous hairs; male surstyli anterodistally dilated; female postpedicel same length as that of male. In A. kishimotoae , frons black; scutum shining, sparsely covered with distinct hairs; male surstyli gradually dilated toward the tip, not anterodistally; female postpedicel smaller than that of male.

Bionomics. Adults were collected from a flower community of Corydalis incisa (Thumb.) Per. in early spring. The larvae probably penetrate into the seed capsules of this flower.

Figures

FIGURES 1–6. Acerocnema incisa sp. nov. 1, Male head and thorax, dorsal view (holotype); 2, Male head, left lateral view; 3, Male sternite V, ventral view; 4, Male terminalia, left lateral view; 5, Male terminalia, posterior view; 6, Female terminalia, left lateral view. Abbreviations: Head—ar, arista; fr, frontal setae; oc, ocellar setae; or, orbital setae; pal, palpus; ppd, postpedicel; prb, proboscis; vte, outer vertical setae; vti, inner vertical setae; vib, vibrissa. Abdomen - aed, aedeagus; cer, cercus; ep, epandrium; epiph, epiphallus; epipr, epiproct; hypr, hypoproct; pm, paramere; st, sternite; sur, surstylus; tg, tergite.